The present invention relates to a load driving device including a pulse driving circuit which repetitively applies a pulse voltage to a resistive load.
Generally, for example, as a load driving device which drives a resistive load, such as a heater which heats a detection element of an oxygen sensor primarily made of a solid electrolyte body, such as zirconia, a load driving device including a pulse driving circuit which has an output terminal connected to the other end of the resistive load with one end grounded and repetitively applies a pulse voltage to the resistive load is used. In the load driving device, abnormality, such as short-circuiting to a ground potential or a power supply potential in a connection path of the pulse driving circuit and the resistive load or disconnection in the connection path, may occur. In particular, when short-circuiting to the ground potential or the power supply potential occurs, the continuous driving of the resistive load results in failure in the pulse driving circuit. For this reason, it is preferable that the load driving device includes an abnormality detection unit for appropriately detecting the occurrence of abnormality.
For example, JP-A-2006-308457 discloses a control device including a level specification unit for specifying which sort of short (short-circuiting) occurs in a path from a driving device to a load device.